A cold standby is a backup environment that is not running during normal operation. When the primary fails, you start the machines or build the stack, restore the latest data, and then redirect traffic.
Why it matters
Cold standby is the cheapest redundancy, because you pay mostly for storage, not compute. The trade-off is the slowest recovery, commonly hours, and potentially larger data loss equal to the age of your last backup. It fits internal tools, staging systems and low-traffic sites where a few hours offline is acceptable. For anything revenue-critical, the long recovery usually costs more than a warmer option.
Example
A small shop keeps nightly database dumps and a server image in object storage. After a host failure, the recovery runbook is:
- Launch a new server from the saved image.
- Restore the most recent dump.
- Lower the DNS TTL beforehand if you can, then update the A record.
If the last backup ran at 02:00 and the failure hit at 15:00, up to 13 hours of orders are gone.
Common mistakes
- Having backups but never restoring one, so corruption or missing files are discovered during the emergency.
- Storing images and backups in the same account or region as the primary.
- Leaving the DNS TTL high so the cutover takes hours to reach users.
Related
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